1902.] F. Finn — Qetieral Notes on Variation in Birds. 159 



fection the rich blue-black body and chestnut wings of the adult, instead 

 of the usual barred plumage of immaturity. Birds resembling the adult 

 in everything except in being duller are quite common. 



The young of the King-crow {Bicrurus ater) and the small 'Indian 

 Cormorant (Phalacrocorax javanicus) are supposed to be mottled with 

 white beneath, but all the nestlings I have seen in Calcutta have been 

 black like adults. Yet the Dicrurus does undoubtedly have a white- 

 spotted immature plumage, and some young Cormorants I reared after- 

 wards moulted out mottled below, so that apparently a reversion may 

 take place at the moult. 



Similarly, the young Pied Hornbills {Anthracoceros alhirostris) fi'e- 

 quently sold here are always coloured like the adult ; but one I knew 

 of moulted out in confinement with white tips and bars to the feathers ; 

 a white-baned feathering being given as the young plumage of the 

 closely-allied ^. corona^ws by Parker (Blanford, F.B.I. Birds, Vol. III., 

 p. 145). 



The young of the common Mynah {Acridotheres tristis), normally 

 resemble the adult except in being duller, but I have seen two with 

 brown heads instead of black ; this is much more common in the young 

 of the allied Bank Mynah {A. gi7iginianus). 



The young females of tlie Golden-backed Woodpecker {Brnchypternus 

 aurantius), are described as having a black forehead, whereas that of 

 the old bird is spotted with white. Often, however, young hens occur 

 in which the forehead is spotted, sometimes as clearly as an adult's. 



D. Variation in Prepotency. 



The silver-grey gander mentioned in the note on the variations of the 

 Gray Goose was an example of spontaneous prepotency. Such a variation 

 in the wild state might easily have produced the white and partially 

 white males in the sexually dimorphic species of the genus Chloephaga ; 

 C. hybrida — the Rock-Goose of Darwin — and C. magellanica, the fami- 

 liar Magellan Goose of waterfowl fanciers, the Upland Goose of the 

 Origin of Species, and a third species barely distinct specifically from 

 C. magellanica — C dispar, in which the male is barred beneath like the 

 female. 



The species C. ruhidiceps, which is extremely like a small female of 

 C niagelhinica, may be taken as one in which no variation in the direc- 

 tion of gray-and-white ganders has appeared, or if it did occur, has not 

 been perpetuated by natural or sexual selection. 



I have come upon some curious instances of the opposite attribute to 

 prepotency in pigeons. In 1894 I crossed a well-developed and fully- 

 adult Black Fantail Cock with a young and hitherto unmated Homer 



